REACT.JS: Difference Between Using npm start and npm run build + serve -s build

When I develop my React application, I utilize the npm install command to set up dependencies and npm start to launch the app. However, for production, I execute npm run build, which generates a build folder, and then I run serve -s build. While the site is accessible, I’ve noticed discrepancies in the UI of certain buttons/elements (like size and borders) compared to when using npm start. There are no error messages during execution, so I’m uncertain about what might be lacking. Could anyone provide insights or suggestions? Here’s a snippet from my Index.js file:

import React from 'react';
import { render } from 'react-dom';
import MainComponent from './MainComponent';
import 'bootstrap/dist/css/bootstrap.min.css';
import { StoreProvider } from 'react-redux';
import myStore from './myStore';

render(
  
    
  ,
  document.getElementById('app')
);

Hey Charlie,

The difference lies in the environments. npm start sets up a development server with hot reloading and more relaxed settings, optimizing for rapid development and debugging. Conversely, npm run build creates an optimized concatenated build with minified files suitable for production.

The UI discrepancies might stem from differences in environment settings or unoptimized styling resources. Make sure your production build includes all necessary CSS and media files. Also, check if there are dependencies requiring different CSS files or configurations in production.

Test styles specifically in production mode to identify any potential className differences or missing assets.